The present invention relates generally to providing a guide for use in performing spinal surgery, in conjunction with systems that use and generate images during medical and surgical procedures, which images assist in executing the procedures and indicate the relative position of various body parts and surgical instruments. In particular the invention relates to a guide, and system and method utilizing the guide, for performing spinal surgery to provide protected access across a spinal disc and into adjacent vertebrae to prepare an implantation space so as to ensure predetermined trajectory and placement of an artificial implant/bone dowel into the implantation space.
Various instruments and methods have been used to prepare adjacent vertebrae of the spine for insertion of a bone dowel or artificial implant. These instruments and methods allow for the removal of disc material from between adjacent vertebrae as well as a portion of each vertebra to form an implantation space or opening. Drill sleeve, tubular member, sheath, working channel, and guard are a few of the names for the protective guide used to guide drills and other disc and bone removal devices into the spine to form the implantation space for receipt of the bone dowel or artificial implant. Certain of the guides have a sharpened end or include teeth for engaging the vertebrae upon application of an impaction force. The guide can be positioned so as to span the disc space and be seated into the adjacent vertebrae to provide protected access to the spine during the process of forming the implantation space. The implantation space spans the disc space and protrudes into each of the adjacent vertebrae along two opposed resected arcs. An example of the procedure for drilling holes across a disc space and instrumentation pertaining thereto are described in U.S. Pat. No. 5,484,437 to Michelson and is incorporated herein by reference.
The use of cylindrical implants is desirable because the surgeon can prepare the recipient site by drilling a cylindrical hole across the disc space and into the adjacent vertebrae. The curved surface of the cylindrical holes drilled into the vertebrae provide for the possibility of tight congruency when the cylindrical hole is fitted with an implant having corresponding cylindrical portions of matched diameter.
Typically, threaded artificial implants, such as the implant disclosed in U.S. Pat. No. 5,015,247 to Michelson, the entire disclosure of which is incorporated herein by reference, are placed into the implantation space between the adjacent vertebrae to directly participate and be incorporated in the ensuing fusion. Threaded bone dowels, such as those taught by Viche may also be placed into the implantation space for the purpose of bridging the opening and to be incorporated into the fusion between the vertebrae. Moreover, artificial implants of the push-in type, such as those disclosed in U.S. Pat. No. 5,593,409 to Michelson and assigned to the assignee of the present application and incorporated herein by reference, may also be inserted into the implantation space formed by the above described instruments and methods.
Whether pushing or threading an implant or dowel into the implantation space, the surgeon attempts to orient the sheath for guiding the formation of the implantation space to remove approximately the same amount of material from each of the vertebra. Once the implant or dowel is implanted, a fluoroscope may be used to assist in determining if proper placement has occurred.
A number of different types of surgical navigation systems have been described that include indications of the relative positions of medical instruments and body parts used in medical or surgical procedures. For example, U.S. Pat. No. 5,383,454 to Bucholz; PCT Application No. PCT/US94/04530 (Publication No. WO 94/24933) to Bucholz; and PCT Application No. PCT/US95/12894 (Publication No. WO 96/11624) to Bucholz et al., the entire disclosures of which are incorporated herein by reference, disclose systems for use during a medical or surgical procedure using scans generated by a scanner prior to the procedure. Surgical navigation systems typically include tracking means such as for example an LED array on the body part, emitters on the medical instruments, a digitizer to track the positions of the body part and the instruments, and a display for the position of an instrument used in a medical procedure relative to a body part.
Procedures for preparing an implantation space in the spine present certain particular challenges to be addressed at specific levels within the spinal column. For example, preforming such a procedure at L4-5 of the spine can raise the following issues: 1) During a posterior approach, significant muscle stripping and tearing is required to reach the L4-5 disc space. Significant post-operative trauma to the patient may result. 2) During an anterior approach, with either a transperitoneal or retroperitoneal, open or laparoscopic approach to the L4-5 disc space, the great vessels lie almost directly on the front of the spinal column at that level. Dissection and manipulation of these vessels may be time-consuming and difficult.
The applicant determined that a retroperitoneal xe2x80x9coblique approachxe2x80x9d to the L-5 disc space can present a preferred surgical solution. The muscle splitting and tearing of the posterior approach is therefore not inevitable, since the oblique approach takes place just anterior to the psoas muscle located laterally along the vertebral column. The oblique approach also allows for an approach slightly posterior of the great vessels lying anterior on the spinal column, thus reducing any risk of injury to the great vessels.
In viewing the spine solely from a lateral fluoro image, the spine surgeon, via this oblique approach, would have a limited ability to see an indication of the depth and direction of their instrumentation as it moves in a posterior lateral fashion across the disc space towards the exiting nerve root.
In light of the foregoing, it would be beneficial in the art for a system and method for the placement of a guide in the spine that provides directional assistance to the surgeon to improve the placement of the guide used in forming the implantation space as well as for use in determining the depth of insertion of instruments passing through the guide, thereby improving the placement of implants and dowels into the implantation space.
Accordingly, the present invention is directed to a guide, system, and method for using the guide in performing spinal surgery to prepare an implantation space across a spinal disc and adjacent vertebrae. More specifically, one object of the present invention is directed to apparatus and procedures for the placement of a guide into the spine using image guided surgery to improve proper placement of the guide through which the implantation space is to be formed and thus proper placement of the implant or dowel.
To achieve this object and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a guide for use in performing spinal surgery to prepare an implantation space across a spinal disc and adjacent vertebrae. The guide is used in conjunction with a computer controlled surgical navigation system employing an energy-detecting array to track positions of the guide in three dimensional space relative to a known reference point. The guide comprises a body for providing protected access to prepare the implantation space across the spinal disc and into the adjacent vertebrae. The body has a passage adapted to receive a bone removal device for forming the implantation space through the body. At least one emitter array is attached to the body for use in identifying the location of the guide relative to the adjacent vertebrae.
The guide may additionally include a disc penetrating extension extending from the body for insertion into the disc space between the adjacent vertebrae and for bearing against endplates of the adjacent vertebrae. A preferred body includes a hollow tube having an end including extensions for penetrating the spine. An emitter array is preferably on each extension of the guide and more preferably includes at least one LED. Preferred arrays include an electrically energizable energy emitter array, known as an active emitter, as well as a reflective surface that reflects signals, known as a passive emitter.
Additionally, the invention includes a system for use in performing spinal surgery to prepare across a spinal disc and adjacent vertebrae an implantation space. The system comprises the above described guide and a computer controlled surgical navigation system employing an energy detecting array to track positions of the guide in three dimensional space relative to a known reference point.
In addition, the invention further comprises a method for performing spinal surgery with a guide used to provide protected access across a spinal disc and into adjacent vertebrae to prepare an implantation space. The method comprises the steps of: attaching a reference array to the vertebrae of interest; registering the location of that vertebrae with a computer controlled surgical navigation system; contacting one end of the guide having at least one emitter array attached thereto to the adjacent vertebrae; employing the surgical navigation system with a computer controller and a digitizer array for communicating with the energy emitter of the guide; positioning the guide in three dimensional space relative to a known reference point system; and forming the implantation space through the guide across the disc space and into a portion of each of the adjacent vertebrae.
In another aspect, the method includes the step of generating a display of the position of the guide. The generating step preferably displays the location of the guide relative to the adjacent vertebrae to provide a view of the axial orientation of the guide relative to each vertebra and/or relative to the adjacent vertebrae. The orientation of the disc penetrating extensions can also be displayed. The location of the tip of an instrument which is placed through the guide can be displayed as well. Identifying the location of the instrument tip passing through the guide permits tracking of tool depth insertion. The generating step may also display the location of the guide relative to the adjacent vertebrae to provide a cross-sectional view of the guide relative to one of an anterior or posterior view of the adjacent vertebrae.
The method may also include the step of emitting a signal from an emitter attached to the guide which is received by an apparatus representatively indicating that signal on a visual display. A preferred method of the present invention also includes the step of implanting an artificial implant, a bone dowel, or other type of bone into the implantation space. The method also may include the step of tracking an artificial implant or bone dowel inserter via an emitter array attached to the inserter. The inserter preferably is configured to pass through the guide. The computer controlled surgical navigation system may be configured to display the inserter as it passes through the guide and more preferably may display both the inserter and the attached artificial implant or bone dowel based on the geometrical configuration of the inserter and of an implant or bone dowel attached thereto.
The objects of the invention are to provide a surgeon with the guide, system, and method to track the guide used in conjunction with a surgical navigation system in such a manner to operate on a patient on the spine to ensure proper orientation of the guide to the spine when forming an implantation space.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in this description.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.